In many applications the benefit of using Radio Frequency Identification (RFID) as a means for a host system to communicate with external components is that it does not require direct contact or even line of sight in order to communicate data. However, in certain applications, there also exist several benefits to utilizing RFID hardware and protocols in the manner of direct contact rather than by generation and modulation of an RF field
Applications wherein contact smart modules are used as a means to store data are very common. Secure credit cards often have a smart module mounted onto the surface of the card. When the card is inserted into a receiver terminal, a set of probes or pins make contact with each of the contacts on the smart module. The data on the smart module memory device is read and processed by a system inside the receiver terminal.
In U.S. Pat. No. 6,298,255, a memory device in the form of a 6-contact smart card memory module is incorporated into an electrophysiological sensor system allowing for the automatic authentication and configuration of the sensor. The smart card memory module contains various data to identify the source of the sensor as well as data regarding the status of the sensor. A biopotential signal monitor and accompanying hardware and software interface read and process the data on the memory module. In this invention, the memory device is located on a rigid substrate that inserts into a mating receptacle. The mating receptacle on the cable contains a 6 pin connector that must align correctly in order to interface with and thus read the data contained by the smart module. A ground guard is used to provide patient protection in the event of a circuit fault. This device does not use RFID memory devices.
In US Patent US2006/0255941 A1, Carrender et al. describe a method by which an RFID chip mounted on a recessed flexible substrate with contacts (strap) can be functionally tested for performance parameters. The method involves directly coupling paired test elements to the paired contacts on an RFID strap and then transmitting test signals to the chip and return signals from the chip. Test data from the chip is transmitted in the return signals, which may include a manufacturer code or a pre-programmed test code. This method provides feedback on the functionality of the RFID assembly.
In U.S. Pat. No. 7,273,173 Forster et al. describes a RFID device detection system which uses both antenna and contact coupling on an RFID transponder—in this patent, the passive RFID device receives power and communicates via conductive transmission lines in an antennaless system. The coupling between the transponder and the reader uses either short range electric field or magnetic field coupling.
In U.S. Pat. No. 7,277,016, Moskowitz et al. describe several means by which RFID tags can be disabled for the purpose of providing an extra layer of security for the data. It is suggested that once an RFID tag is disabled by way of damaging the antenna, that the short antenna stubs may be electrically contacted by mechanical probes thus allowing the tag to be read once via direct contact. However, the method by which this can be achieved is not presented nor discussed in this patent publication.
In US Patent 2004/0008123A1, Carrender et al. describe a system for monitoring pharmaceuticals that uses an RFID tag mounted in the cap of a tablet container which stores various information relating to the pharmaceuticals, such as data about the manufacture, distribution and sale thereof. The RFID tag is also fitted with capacitive sensors that sense the position of the tablet container cap. A standard RFID reader is used to wirelessly read the data from the RFID tag.
As with contact smart card memory module described above, there is also a commercially available product, dual interface ICs which incorporate multi-functional chips for applications where a card may need to be read by a contact or a contactless system. For example, an SLE66CL80PE(M) (Infineon Corporation) features ISO/IEC 14443 Type B (RFID protocol) contactless interfaces as well as an ISO/IEC 7816 contact-based interface, on a single chip. In direct contact mode, the contact-based interface is used while when wireless communication is required, the contactless interface is engaged. The contactless protocol is not used when the card is read in direct contact mode.